Rods with threads therein for use as filter rods for smoking articles are known. Examples of such rods are taught in U.S. Pat. No. 4,281,671 and US 2005/0255978, although there are a number of problems associated with the known methods for preparing the rods. For example, the methodology taught in U.S. Pat. No. 4,281,671 does not reliably allow manufacturers to accurately place the threads inside the rods. If, for example, it was desirous to have the thread running along the central axis of the rod then the method taught in U.S. Pat. No. 4,281,671 does not allow workers to create with some degree of accuracy such embodiments, meaning that the threads are prone to being off-centre. This can result in uneven migration of, for example, the menthol flavourant which may be impregnated into the thread, which in some cases can result in spotting or similar spoilage of the casings or coverings or wrappers wrapped around filters etc. A problem with the methodology taught in US 2005/0255978 is that it is not well suited for the application of volatile flavourants, such as menthol, since the flavourants are coated onto the solid support at a location quite remote from the rod forming means.
A further problem associated with the above prior art is that the apparatuses disclosed therein to produce rods for use in smoking articles are not capable of locating two or more threads in the produced rod, even less doing so with an acceptable degree of accuracy, nor do they enable the position of such threads in the rod to be readily and accurately altered.
A problem with such known filters rods having only a single thread therein is that they provide a very limited capability for having distinctive characteristics to enable product distinction by the consumer. Furthermore, if it is intended to introduce flavourants into the threads, single-thread filter rods provide a very simple and limited flavour delivery capability, not allowing any flavour combinations or relative flavour strength variations to be achieved.
Accordingly, the present invention seeks to overcome the above problems of the prior art.